The present invention relates to a heat exchanger made of an aluminum alloy, and more particularly to a heat exchanger with a radiator and an oil cooler integrated that is produced by using aluminum alloy brazing sheets.
A heat exchanger having a radiator and an oil cooler in combination is manufactured by assembling a radiator core part (10) and an oil cooler part (11) (oil passages (7) formed by joining brazing sheets (8) are illustrated in a simplified manner in the drawings) and then mechanically associating them with tanks (6), for example, as shown perspectively in FIG. 4.
Herein, as is apparent from FIG. 5 showing a perspective view, the radiator is made up of the radiator core part (10), comprising flat tubes (3), thin fins (1), side supports (12), and headers (4), and the tanks (6). Each of the corrugated thin fins (1) is formed between the flat tubes (3), with the corrugated thin fin integrated with the flat tubes, and the ends of the flat tubes (3) are open to space (2) formed by the headers (4) and the tanks (6), so that a high-temperature refrigerant is passed from the space in one tank through the flat tubes (3) to another space (2) of the other tank (6), to recirculate the refrigerant, whose temperature has been lowered due to the heat exchange at the tubes (3) and the fins (1).
The radiator part is assembled as follows: as the tube material and the header material, brazing sheets are used, wherein the core material is, for example, JIS 3003 alloy; the inner side on the core material, that is, the side to which the refrigerant constantly contacts is coated with JIS 7072 alloy as a lining material; and the outer side on the core material is clad with a usual filler material, such as JIS 4045; and the tubes and the headers are integrated with corrugated fins and other members by brazing.
In the oil cooler part (11), the oil passages (7) formed by joining the brazing sheets (8) extend through the space in the tank (2), and an oil having a high temperature passing through the passages (7) is cooled with the refrigerant passing through the space (2). For forming the oil passages, brazing sheets are used, wherein, as the core material, for example, JIS 3003 alloy is used; the outer side on the core material, that is, the side to which the refrigerant constantly contacts is clad, for example, with JIS 7072 alloy, and the inner side on the core material is clad, usually, with a filler material, such as JIS 4045. Generally the brazing sheets are brazed by heating them to a temperature of about 600xc2x0 C.
Thus, the radiator part and the oil cooler part are assembled by brazing at a temperature of about 600xc2x0 C. The brazing is carried out, for example, by the flux brazing method or the non-corrosive flux brazing method, wherein a non-corrosive flux is used.
However, conventionally the tank (6) is generally made of a resin material, and the tank (6) has to be attached in a step separated from the step of assembling the radiator part and the oil cooler part by brazing, so that there is a difficulty that additional step is required. Further, in such a heat exchanger, the part between the resin tank (6) and the header (4) that is fastened, is required to be caulked through a resin packing (5) or the like, which leads to a defect that crevice corrosion is apt to take place at the boundary between the resin packing (5) and the header (4).
Further, in recent years, recycling of material has attracted attention in view of effective use of resources on the earth. Heat exchangers for automobiles are removed when the automobiles are disassembled, and they are melted as aluminum alloys for recycling. However, as shown in FIG. 4, when the heat exchanger has, as the tank (6), a tank made of resin, the resin tank has to be removed purposely when the automobile is disassembled, and that becomes a bottleneck in the recycling process.
Therefore, it is desirable that the tank also be made of an aluminum alloy and be assembled simultaneously by the brazing technique. However, after that brazing, the oil cooler part is brazed with it covered with the tank. Therefore, if the brazing of the oil cooler is incomplete, it cannot be repaired anymore. Thus, it is required that the brazing be effected completely, but it is conventionally difficult due to the following reason. Since the oil cooler part is covered with the tank, the temperature of the brazing is not elevated satisfactorily, and defective brazing is apt to occur. Further, if the heating is carried out to elevate the temperature satisfactorily so as not to cause defective brazing, the brazing temperature is elevated excessively for the radiator part, and thus inconveniently the filler material diffuses into the radiator tubes and the fins. Further, in the oil cooler, since the brazed part is in contact with a refrigerant, local corrosion is apt to occur due to the potential difference between the brazed part and the core material part. This problem cannot be solved by brazing by the conventional brazing technique.
Therefore, an object of the present invention is to provide a heat exchanger that is made of an aluminum alloy by using an aluminum material instead of a resin tank, can be easily recycled, is excellent in corrosion resistance, and can be produced without requiring a step of caulking a tank.
Other and further objects, features, and advantages of the invention will appear more fully from the following description, taken in connection with the accompanying drawings.
The above object has been attained by providing a heat exchanger made of an aluminum alloy having the following constitution.
According to the present invention there are provided;
(1) A heat exchanger made of an aluminum alloy having a radiator part and an oil cooler part in combination and assembled integrally by the brazing method, wherein a refrigerant tank for covering and sealing said oil cooler part is made of an aluminum alloy, an aluminum alloy containing Si in an amount from more than 7.0 wt % to 12.0 wt %, Fe in an amount from more than 0.05 wt % to 0.5 wt %, Cu in an amount from more than 0.4 wt % to 8.0 wt %, Zn in an amount from more than 0.5 wt % to 10.0 wt %, and the balance of aluminum and inevitable impurities is used as a filler material of brazing sheets that are used for said oil cooler part and are brazed in said tank, and said refrigerant tank is assembled integrally with said radiator part and said oil cooler part by brazing with said brazing material; and
(2) A heat exchanger made of an aluminum alloy having a radiator part and an oil cooler part in combination and assembled integrally by the brazing method, wherein a refrigerant tank for covering and sealing said oil cooler part is made of an aluminum alloy, an aluminum alloy containing Si in an amount from more than 7.0 wt % to 12.0 wt %, Fe in an amount from more than 0.05 wt % to 0.5 wt %, Cu in an amount from more than 0.4 wt % to 8.0 wt %, Zn in an amount from more than 0.5 wt % to 10.0 wt %, one or both of In in an amount from more than 0.002 wt % to 0.3 wt % and Sn in an amount from more than 0.002 wt % to 0.3 wt %, and the balance of aluminum and inevitable impurities is used as a filler material of brazing sheets that are used for said oil cooler part and are brazed in said tank, and said refrigerant tank is assembled integrally with said radiator part and said oil cooler part by brazing with said brazing material.
In this invention, the radiator part and the oil cooler part can be assembled integrally in one step brazing.